SEBACEOUS FLUIDS. 



361 



brownish or yellowish pigmentary granules. The tube forming the gland contains a clear 

 fluid mixed with a granular substance containing cells. 



In addition to the ceruminous glands of the ear, numerous sebaceous follicles are found 

 connected with the hair-follicles here, as in other parts provided with hair. The arrange- 

 ment of the ordinary sebaceous glands and the ceruminous glands, which are situated in 

 different planes in the subcutaneous structure, is shown in Fig. 100. 



The Meibomian glands of the eyelids have essentially the same structure as the ordi- 

 nary sebaceous glands. Their ducts, however, are longer, and the terminal follicles are 

 arranged in a peculiar manner by the sides of the tubes along their entire length. 

 These glands are situated partly in the substance of the tarsal cartilages, between 

 their posterior surfaces and the conjunctival mucous membrane. They are placed at 

 right angles to the free border of the eyelids, opening upon the inner edge and occupy- 

 ing the entire width of the cartilages. From twenty-five to thirty glands are found in the 

 upper, and from twenty to twenty-five, in the lower lid. 



Each Meibomian gland consists of a nearly straight excretory duct, from ^-^ to -^ 

 of an inch in diameter, communicating laterally with numerous compound racemose 

 acini, or collections of follicles, measuring from -^ to T of an inch. From fifteen to 

 twenty of these collections of follicles are found on either side of the duct in glands 

 of medium length. Most of the excretory ducts are nearly straight, but some are 

 turned upon themselves near their upper extremity. The general arrangement of these 

 glands is shown in Fig. 101. 



In general structure there is little if any 

 difference between the terminal follicles of the 

 Meibomian glands and the follicles of the ordi- 

 nary sebaceous glands. They are lined with 

 cells measuring from ^V "o to T^HF f an mc ^ ^ n 

 diameter. These cells contain numerous fatty 

 globules, but they do not coalesce into large 

 drops, such as are often seen in the ordinary 

 sebaceous cells. The follicles and ducts are 

 filled with the whitish, oleaginous matter which 

 constitutes the Meibomian secretion, or the 

 sebum palpebrale. 



In addition to the Meibomian secretion, the 

 edges of the palpebral orifice receive a small 

 amount of secretion from ordinary sebaceous 

 glands of the compound racemose variety (cili- 

 ary glands), which are appended in pairs to each 

 of the follicles of the eyelashes, and from the 

 sebaceous glands attached to the small hairs of 

 the caruncula lachrymalis. 



Ordinary Sebaceous Matter. Although it 

 may be inferred, from the great number of 

 sebaceous glands opening upon the cutaneous Fio. ^^^^^^^^^ 

 surface, that the amount of sebaceous matter ^ ^ free border of the Hd ; 2, 2, anterior lip pene- 

 must be considerable, it has been impossible to 

 collect the normal fluid in quantity sufficient for 

 ultimate analysis. In certain parts, as the skin 

 of the nose, where the glands are particularly 

 abundant, a certain amount of oily secretion is 



sometimes observed, giving to the surface a greasy, glistening aspect. This may be 

 absorbed by paper, giving it the well-known appearance produced by oily matters, and it 



, , , 



trated by the eyelashes ; 8, 3, posterior lip, with 

 the openings of the Mcil.omian plarnls: 4. n pl.iml 

 passing obliquely at the summit ; 5 another 

 gland bent upon itself; 6. 0. two plands in the 

 form of racemose plands at their onpin ; 7, a 

 very small gland ; 8, a medium-sized gland. 



